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<h1 class="title">arrow.cpp 示例文件</h1>
<span class="subtitle">graphicsview/diagramscene/arrow.cpp</span>
<!-- $$$graphicsview/diagramscene/arrow.cpp-description -->
<div class="descr"> <a name="details"></a>
<pre class="cpp">

  <span class="comment">/****************************************************************************
  **
  ** Copyright (C) 2016 The Qt Company Ltd.
  ** Contact: https://www.qt.io/licensing/
  **
  ** This file is part of the examples of the Qt Toolkit.
  **
  ** $QT_BEGIN_LICENSE:BSD$
  ** Commercial License Usage
  ** Licensees holding valid commercial Qt licenses may use this file in
  ** accordance with the commercial license agreement provided with the
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  ** BSD License Usage
  ** Alternatively, you may use this file under the terms of the BSD license
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  ** &quot;Redistribution and use in source and binary forms, with or without
  ** modification, are permitted provided that the following conditions are
  ** met:
  **   * Redistributions of source code must retain the above copyright
  **     notice, this list of conditions and the following disclaimer.
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  ****************************************************************************/</span>

  <span class="preprocessor">#include &quot;arrow.h&quot;</span>

  <span class="preprocessor">#include &lt;qmath.h&gt;</span>
  <span class="preprocessor">#include &lt;QPen&gt;</span>
  <span class="preprocessor">#include &lt;QPainter&gt;</span>

  Arrow<span class="operator">::</span>Arrow(DiagramItem <span class="operator">*</span>startItem<span class="operator">,</span> DiagramItem <span class="operator">*</span>endItem<span class="operator">,</span> <span class="type"><a href="qgraphicsitem.html">QGraphicsItem</a></span> <span class="operator">*</span>parent)
      : <span class="type"><a href="qgraphicslineitem.html">QGraphicsLineItem</a></span>(parent)
  {
      myStartItem <span class="operator">=</span> startItem;
      myEndItem <span class="operator">=</span> endItem;
      setFlag(<span class="type"><a href="qgraphicsitem.html">QGraphicsItem</a></span><span class="operator">::</span>ItemIsSelectable<span class="operator">,</span> <span class="keyword">true</span>);
      myColor <span class="operator">=</span> <span class="type"><a href="../qtcore/qt.html">Qt</a></span><span class="operator">::</span>black;
      setPen(<span class="type"><a href="../qtgui/qpen.html">QPen</a></span>(myColor<span class="operator">,</span> <span class="number">2</span><span class="operator">,</span> <span class="type"><a href="../qtcore/qt.html">Qt</a></span><span class="operator">::</span>SolidLine<span class="operator">,</span> <span class="type"><a href="../qtcore/qt.html">Qt</a></span><span class="operator">::</span>RoundCap<span class="operator">,</span> <span class="type"><a href="../qtcore/qt.html">Qt</a></span><span class="operator">::</span>RoundJoin));
  }

  <span class="type"><a href="../qtcore/qrectf.html">QRectF</a></span> Arrow<span class="operator">::</span>boundingRect() <span class="keyword">const</span>
  {
      <span class="type"><a href="../qtcore/qtglobal.html#qreal-typedef">qreal</a></span> extra <span class="operator">=</span> (pen()<span class="operator">.</span>width() <span class="operator">+</span> <span class="number">20</span>) <span class="operator">/</span> <span class="number">2.0</span>;

      <span class="keyword">return</span> <span class="type"><a href="../qtcore/qrectf.html">QRectF</a></span>(line()<span class="operator">.</span>p1()<span class="operator">,</span> <span class="type"><a href="../qtcore/qsizef.html">QSizeF</a></span>(line()<span class="operator">.</span>p2()<span class="operator">.</span>x() <span class="operator">-</span> line()<span class="operator">.</span>p1()<span class="operator">.</span>x()<span class="operator">,</span>
                                        line()<span class="operator">.</span>p2()<span class="operator">.</span>y() <span class="operator">-</span> line()<span class="operator">.</span>p1()<span class="operator">.</span>y()))
          <span class="operator">.</span>normalized()
          <span class="operator">.</span>adjusted(<span class="operator">-</span>extra<span class="operator">,</span> <span class="operator">-</span>extra<span class="operator">,</span> extra<span class="operator">,</span> extra);
  }

  <span class="type"><a href="../qtgui/qpainterpath.html">QPainterPath</a></span> Arrow<span class="operator">::</span>shape() <span class="keyword">const</span>
  {
      <span class="type"><a href="../qtgui/qpainterpath.html">QPainterPath</a></span> path <span class="operator">=</span> <span class="type"><a href="qgraphicslineitem.html">QGraphicsLineItem</a></span><span class="operator">::</span>shape();
      path<span class="operator">.</span>addPolygon(arrowHead);
      <span class="keyword">return</span> path;
  }

  <span class="type">void</span> Arrow<span class="operator">::</span>updatePosition()
  {
      <span class="type"><a href="../qtcore/qlinef.html">QLineF</a></span> line(mapFromItem(myStartItem<span class="operator">,</span> <span class="number">0</span><span class="operator">,</span> <span class="number">0</span>)<span class="operator">,</span> mapFromItem(myEndItem<span class="operator">,</span> <span class="number">0</span><span class="operator">,</span> <span class="number">0</span>));
      setLine(line);
  }

  <span class="type">void</span> Arrow<span class="operator">::</span>paint(<span class="type"><a href="../qtgui/qpainter.html">QPainter</a></span> <span class="operator">*</span>painter<span class="operator">,</span> <span class="keyword">const</span> <span class="type"><a href="qstyleoptiongraphicsitem.html">QStyleOptionGraphicsItem</a></span> <span class="operator">*</span><span class="operator">,</span>
            <span class="type"><a href="qwidget.html">QWidget</a></span> <span class="operator">*</span>)
  {
      <span class="keyword">if</span> (myStartItem<span class="operator">-</span><span class="operator">&gt;</span>collidesWithItem(myEndItem))
          <span class="keyword">return</span>;

      <span class="type"><a href="../qtgui/qpen.html">QPen</a></span> myPen <span class="operator">=</span> pen();
      myPen<span class="operator">.</span>setColor(myColor);
      <span class="type"><a href="../qtcore/qtglobal.html#qreal-typedef">qreal</a></span> arrowSize <span class="operator">=</span> <span class="number">20</span>;
      painter<span class="operator">-</span><span class="operator">&gt;</span>setPen(myPen);
      painter<span class="operator">-</span><span class="operator">&gt;</span>setBrush(myColor);

      <span class="type"><a href="../qtcore/qlinef.html">QLineF</a></span> centerLine(myStartItem<span class="operator">-</span><span class="operator">&gt;</span>pos()<span class="operator">,</span> myEndItem<span class="operator">-</span><span class="operator">&gt;</span>pos());
      <span class="type"><a href="../qtgui/qpolygonf.html">QPolygonF</a></span> endPolygon <span class="operator">=</span> myEndItem<span class="operator">-</span><span class="operator">&gt;</span>polygon();
      <span class="type"><a href="../qtcore/qpointf.html">QPointF</a></span> p1 <span class="operator">=</span> endPolygon<span class="operator">.</span>first() <span class="operator">+</span> myEndItem<span class="operator">-</span><span class="operator">&gt;</span>pos();
      <span class="type"><a href="../qtcore/qpointf.html">QPointF</a></span> p2;
      <span class="type"><a href="../qtcore/qpointf.html">QPointF</a></span> intersectPoint;
      <span class="type"><a href="../qtcore/qlinef.html">QLineF</a></span> polyLine;
      <span class="keyword">for</span> (<span class="type">int</span> i <span class="operator">=</span> <span class="number">1</span>; i <span class="operator">&lt;</span> endPolygon<span class="operator">.</span>count(); <span class="operator">+</span><span class="operator">+</span>i) {
          p2 <span class="operator">=</span> endPolygon<span class="operator">.</span>at(i) <span class="operator">+</span> myEndItem<span class="operator">-</span><span class="operator">&gt;</span>pos();
          polyLine <span class="operator">=</span> <span class="type"><a href="../qtcore/qlinef.html">QLineF</a></span>(p1<span class="operator">,</span> p2);
          <span class="type"><a href="../qtcore/qlinef.html">QLineF</a></span><span class="operator">::</span>IntersectType intersectType <span class="operator">=</span>
              polyLine<span class="operator">.</span>intersect(centerLine<span class="operator">,</span> <span class="operator">&amp;</span>intersectPoint);
          <span class="keyword">if</span> (intersectType <span class="operator">=</span><span class="operator">=</span> <span class="type"><a href="../qtcore/qlinef.html">QLineF</a></span><span class="operator">::</span>BoundedIntersection)
              <span class="keyword">break</span>;
          p1 <span class="operator">=</span> p2;
      }

      setLine(<span class="type"><a href="../qtcore/qlinef.html">QLineF</a></span>(intersectPoint<span class="operator">,</span> myStartItem<span class="operator">-</span><span class="operator">&gt;</span>pos()));

      <span class="type">double</span> angle <span class="operator">=</span> std<span class="operator">::</span>atan2(<span class="operator">-</span>line()<span class="operator">.</span>dy()<span class="operator">,</span> line()<span class="operator">.</span>dx());

      <span class="type"><a href="../qtcore/qpointf.html">QPointF</a></span> arrowP1 <span class="operator">=</span> line()<span class="operator">.</span>p1() <span class="operator">+</span> <span class="type"><a href="../qtcore/qpointf.html">QPointF</a></span>(sin(angle <span class="operator">+</span> M_PI <span class="operator">/</span> <span class="number">3</span>) <span class="operator">*</span> arrowSize<span class="operator">,</span>
                                      cos(angle <span class="operator">+</span> M_PI <span class="operator">/</span> <span class="number">3</span>) <span class="operator">*</span> arrowSize);
      <span class="type"><a href="../qtcore/qpointf.html">QPointF</a></span> arrowP2 <span class="operator">=</span> line()<span class="operator">.</span>p1() <span class="operator">+</span> <span class="type"><a href="../qtcore/qpointf.html">QPointF</a></span>(sin(angle <span class="operator">+</span> M_PI <span class="operator">-</span> M_PI <span class="operator">/</span> <span class="number">3</span>) <span class="operator">*</span> arrowSize<span class="operator">,</span>
                                      cos(angle <span class="operator">+</span> M_PI <span class="operator">-</span> M_PI <span class="operator">/</span> <span class="number">3</span>) <span class="operator">*</span> arrowSize);

      arrowHead<span class="operator">.</span>clear();
      arrowHead <span class="operator">&lt;</span><span class="operator">&lt;</span> line()<span class="operator">.</span>p1() <span class="operator">&lt;</span><span class="operator">&lt;</span> arrowP1 <span class="operator">&lt;</span><span class="operator">&lt;</span> arrowP2;
      painter<span class="operator">-</span><span class="operator">&gt;</span>drawLine(line());
      painter<span class="operator">-</span><span class="operator">&gt;</span>drawPolygon(arrowHead);
      <span class="keyword">if</span> (isSelected()) {
          painter<span class="operator">-</span><span class="operator">&gt;</span>setPen(<span class="type"><a href="../qtgui/qpen.html">QPen</a></span>(myColor<span class="operator">,</span> <span class="number">1</span><span class="operator">,</span> <span class="type"><a href="../qtcore/qt.html">Qt</a></span><span class="operator">::</span>DashLine));
          <span class="type"><a href="../qtcore/qlinef.html">QLineF</a></span> myLine <span class="operator">=</span> line();
          myLine<span class="operator">.</span>translate(<span class="number">0</span><span class="operator">,</span> <span class="number">4.0</span>);
          painter<span class="operator">-</span><span class="operator">&gt;</span>drawLine(myLine);
          myLine<span class="operator">.</span>translate(<span class="number">0</span><span class="operator">,</span><span class="operator">-</span><span class="number">8.0</span>);
          painter<span class="operator">-</span><span class="operator">&gt;</span>drawLine(myLine);
      }
  }

</pre>
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<!-- @@@graphicsview/diagramscene/arrow.cpp -->
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